1. Technical Field
The technical field relates to median filtering, and more particularly to a median filtering method that is adaptive for realizing vivid and clear picture quality by distinguishing digital noise in video data and replacing the digital noise by use of a median filter.
2. Description of the Related Art
Digital noise greatly deteriorates visual picture quality in producing a display. In order to improve this, a median filter extracts an intermediate value among gray level values within a fixed area and replaces the digital noise with the intermediate value, thereby replacing the digital noise.
As shown in FIG. 1, a median filter of the related art has each pixel arranged in a block of fixed unit area. As shown in FIG. 2, the gray level value of each pixel is arranged in an ascending order or descending order within the unit area block, and an intermediate value is selected. As shown in FIG. 3, the data of a central pixel within the unit area is replaced with the intermediate value. If a similar median filter is used, as is shown in FIG. 4, the digital noise is removed and the deterioration of picture quality can be prevented. In the case of a still image or text image where all the central pixel data are replaced with another value through the median filter the result is that the picture quality of an image using the median filter is more deteriorated than the existing image. Furthermore, because the gray level values of all the pixels located within the unit area should be arranged and the intermediate value should be extracted, there is a problem in that the capacity of the filter can be large, as arranging the gray values and extracting the intermediate value can take a long time and calculating the replacement value is complicated.